In message op.u7ukdzz6m4iaeb@dell, Fig writes

Yesterday's evening peak Circle line was suspend anti-clockwise
(according to a txt from TfL). How can line that is circular in name
only be suspended in one direction?

Because it is now tea-cup shaped, rather than merely circular (the end
of the teacup handle being Hammersmith).

Trains that arrive at Edgware Road, having done a clockwise loop,
normally reverse and run anticlockwise, later passing through Edgware
Road again on their way to Hammersmith (where they reverse).

If there is no anticlockwise service, a train having down a clockwise
circuit to Edgware Road reverses and runs straight back to Hammersmith
instead of doing an anticlockwise circuit. It then reverses at
Hammersmith and sets off for Edgware Road to start another clockwise
loop. i.e.:

Normal operation:

Ham'smith - EW - clockwise - EW - anticlockwise - EW - Ham'smith

Operation with no anticlockwise service

Hammersmith - EW - clockwise - EW - Hammersmith
--
Paul Terry